1. Field of the Invention
The present invention relates to the functioning of a scroll wheel. The meaning of the term “scrolling” on a computer screen or other type of display is well-known. The most common use of scroll wheels is as part of computer mice, but it is also used on certain types of control panels. Turning of a scroll wheel usually effects vertical scrolling. Left or right scrolling can sometimes be effected by pushing the scroll wheel left or right, respectively. Often, a scroll wheel will have a built-in click button that can be customized to perform a desired action.
2. Description of the Prior Art
For known scroll wheels, turning the scroll wheel in a downward direction, towards the user, results in an upward motion of content displayed on the display, and vice versa. This works well for short and slow scrolling. To keep down costs, a standard scroll wheel is usually made out of plastic and sometimes has a rubber rim. Such a wheel has a small weight and thus a small moment of inertia. The bearing friction in such a wheel is also somewhat high, another result of low-cost manufacturing. Such a wheel is not well-suited for so-called free spin, where the wheel can rotate many times before stopping due to friction. Even when the wheel is rotated quickly initiated with a quick motion of the finger, it will stop before achieving a 360 degree rotation. Scrolling through a large document thus has to be performed by repeatedly turning the wheel and lifting one's the finger. This is uncomfortable and inefficient. A wheel made partly of metal and with bearings designed for low friction can allow some amount of free spin and thus fast scrolling. However, this is a costly solution, partly due to the somewhat high cost of a metal wheel and partly due to a higher cost of manufacturing bearings having the required low friction. Furthermore, most people prefer that the scroll wheel is capable of scrolling in small, well-defined steps enabling for instance scrolling in steps of one half line in a word-processing software program. If the wheel is to be able to perform free spin, there must be a built-in motor that can disable this functionality at high rotation speeds. Computer mice with such functionality do exist. They typically consist of some hundred single parts, and the result is that manufacturing costs are double or more compared to standard computer mice. Because of the high price, computer mice having free spin capability are not very common. Another reason is that when using free spin, one may lose the feeling of the amount of scrolling that is taking place.